Study Ontreatment And Utilization Of Electrolytic Manganese Residue

Electrolytic manganese residue, containing high water content, is a kind of industrial solid waste generated from leaching manganese carbonate with sulfuric acid. In recent years, with the rapid development of electrolytic manganese industry in China, it has increasingly become a critical problem about the treatment and utilization of electrolytic manganese residue. At present, due to the economic and technical reasons, most of the electrolytic manganese residues are deposited in store yards without any treatment. By the accumulation, the untreated waste residue becomes seriously dangerous pollution sources for the environment. Therefore, comprehensive utilization of electrolytic manganese residue can not only reduce environmental pollution, but also bring huge benefits. And it is an effective way for sustainable development.In this thesis, the electrolytic manganese residue was from a plant in Chongqing. In order to utilize the electrolytic manganese residue, various analytic methods were required to characterize its basic properties firstly. Secondly, based on the analysis results, the process and its operation conditions on the electrolytic manganese residue pretreatment, manganese and ammonium recovery were studied. At last, the utilization on the residue from the second procedure above was analyzed and evaluated.Conclusions are as follows.The particle size of electrolytic manganese residue is small, and most particle is less than 80μm. It is mainly composed of gypsum phase, quartz phase, pyrolusite phase and manganite phase, etc., and the elements mainly contain Si,Al,Fe,N,Mn,Ca, of whose percentage calculated by the content of oxide are as follows,silica (35.43%), aluminum oxide (11.48%), ferric oxide (5.40%), ammonium sulfate (7.9%), manganese oxide (3.79%), calcium oxide (8.44%). Kinds of elements are contained in the electrolytic manganese residue, which mainly presents mixed stacking structure formed by needle, columnar shaped crystal particles with other substances,and the various particles are staggered and overlapped with each other.The new method's conditions on leaching manganese from the residue were studied in the process of washing. And the feasibility with distilled water as the leaching agent was identified. By the experiments, It is known that when m(residue): v(distilled water) = 1:5, the reaction stirred at room temperature for 2h, the leaching rate of manganese element from manganese residue reaches 93.8%. In the stage of recovery manganese, divalent manganese in the solution could be recovered through manganese carbonate precipitation. During the precipitation with ammonium carbonate as the precipitant, the factors impacting the recovery of manganese were investigated, The results show that when n(CO32+):n(Mn2+)=1.3:1,C(flocculant)=0.4 mg/L,pH =7, stirring speed is 80 r/min and reaction time reaches60 min, the recovery rate of Mn2+ is up to 99.8%. The purity of the recovered manganese carbonate comes to 88.9%, which can be used to produce electrolytic manganese instead of manganese ore well.In the stage of recovering soluble nitrogen from electrolytic manganese residue, aluminum ammonium sulfate crystallization was applied, and the influence of precipitant dosage, reaction temperature, pH value and reaction time on ammonia nitrogen recovery rate was discussed. The results show that when n((NH4)2SO4):n(Al2(SO4)3)= 1:1,pH =2.5, reaction temperature is 95℃, and reaction time maintains 2h, the recovery rate of ammonia nitrogen is more than 95.2%. And the crystal particles obtained are of irregular shape, with good dispersion, no agglomeration, and the purity is up to 93.1%.The impact of different washing time on characteristics of dissolved sulfate was explored. Results show that when the washing time is 60 min, the soluble sulfate in electrolytic manganese residue has been almost dissolved.